Zip strips for molding of infused fiberglass products

ABSTRACT

A method of removing a vacuum bag from a composite mold. Removable strips are placed around the perimeter of the component parts and across the parts to create natural break points in the consumable materials used during manufacture of a composite product, e.g. wind turbine blade. The vacuum bag, and other consumable layers, are placed over the removable strip such that when the strips are pulled, the strip tears, in a controlled and complete manner, through each layer of consumables. This eliminates the need to use a knife/scissor to remove the finished product, thereby avoiding risk of injury.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 USC 119 of priority to U.S.Provisional Application No. 62/667,068 filed May 4, 2018, the entirecontents of which are hereby incorporated by reference.

BACKGROUND OF THE DISCLOSED SUBJECT MATTER Field of the DisclosedSubject Matter

The disclosed subject matter relates to a system and correspondingmethod for the manufacture of fiber reinforced polymer compositemanufacturing, e.g., wind turbine blades. Particularly, the presentdisclosed subject matter provides for a novel technique fordisassembling the apparatus, e.g. vacuum bag(s), employed duringmanufacture of composite products.

DESCRIPTION OF RELATED ART

A variety of methods and systems are known for the manufacture of windturbine blades. Generally, Vacuum Assisted Resin Transfer Molding(VARTM) process is widely used in the manufacture of wind turbine bladesbecause of the lower cost compared to autoclaving. During the process offilling the mold, a vacuum which is under-pressure or negative pressure,is generated via vacuum outlets in the mold cavity, whereby liquidpolymer is drawn into the mold cavity via the inlet channels in order tofill the mold cavity. From the inlet channels the polymer disperses inall directions in the mold cavity due to the negative pressure as a flowfront moves towards the vacuum channels. Vacuum infusion techniquestypically employ a rigid mold part and a resilient mold part in the formof a vacuum bag.

Resin transfer molding (RTM) is a manufacturing method, which is similarto VARTM. In RTM the liquid resin is not drawn into the mold cavity dueto a vacuum generated in the mold cavity. Instead the liquid resin isforced into the mold cavity via an overpressure at the inlet side.

Prepreg molding is a method in which reinforcement fibers arepre-impregnated with a pre-catalysed resin. The resin is typically solidor near-solid at room temperature. The prepregs are arranged by hand ormachine onto a mold surface, vacuum bagged and then heated to atemperature, where the resin is allowed to reflow and eventually cured.This method has the main advantage that the resin content in the fibermaterial is accurately set beforehand. The prepregs are easy and cleanto work with and make automation and labor saving feasible. Thedisadvantage with prepregs is that the material cost is higher than fornon-impregnated fibers. Further, the core material need to be made of amaterial, which is able to withstand the process temperatures needed forbringing the resin to reflow. Prepreg molding may be used both inconnection with a RIM and a VARTM process.

Some exemplary infusion techniques are disclosed in U.S. Pat. Nos.9,599,094 and 8,123,883, the entirety of each is hereby incorporated byreference. Such conventional techniques require substantial cutting ofthe vacuum bag to remove the bag from the mold upon completion of theresin curing. This is undesirable in that the cutting operation istypically performed manually, thereby putting employees at risk ofinjury. Additionally, the conventional cutting techniques requiresignificant tooling and complimentary mold structure (e.g. peripheralcutting channel 26 as disclosed in U.S. Pat. No. 8,123,883) in anattempt to avoid damage to the manufactured part.

There thus remains a need for an efficient and economic method andsystem for vacuum bag removal that avoids the aforementioneddisadvantages associated with conventional cutting and bag removaltechniques. In the manufacturing of wind turbine blades, which are largecomponents, there is a substantial amount of knife work necessary to cutconsumables into manageable size pieces for removal. Using this processit eliminates 99% of the knife work. In addition it provides an idealsurface finish for applying tacky tape for a perimeter bag to retain thepart in the mold.

SUMMARY OF THE DISCLOSED SUBJECT MATTER

The purpose and advantages of the disclosed subject matter will be setforth in and apparent from the description that follows, as well as willbe learned by practice of the disclosed subject matter. Additionaladvantages of the disclosed subject matter will be realized and attainedby the methods and systems particularly pointed out in the writtendescription and claims hereof, as well as from the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the disclosed subject matter, as embodied and broadly described, thedisclosed subject matter includes a method of removing a vacuum bag froma wind turbine blade mold comprising: forming a wind turbine bladecomponent within a mold; providing at least one removable strips, theremovable strip(s) disposed around at least a portion of the perimeterof a component part(s), disposing at least one consumable layer(s) abovea removable strip; disposing a portion of a vacuum bag above a removablestrip; pulling the removable strip, the pulling force tearing throughthe consumable layer(s) and the vacuum bag.

In some embodiments, the removable strip tears through the consumablelayers in a predetermined path, and has thickness of approximately 0.028inches, a width of approximately 0.5 inches, a break strength ofapproximately 820 pounds, and a melting point of approximately 490°Fahrenheit.

In some embodiments, at least one removable strip(s) is placed directlyon glass. Once all the removable strips are removed, the consumablelayer(s) and vacuum bag are tied with the removable strips.

In some embodiments, the removable strips impart a recess in thecomponent part after removal, and a tacky tape is then applied at/withinthe recess.

In some embodiments, at least one removable strip(s) is disposed aroundthe mold on a clamp edge between a top clamp edge and a bottom clampedge.

In some embodiments, at least one removable strip(s) has a first enddisposed at 1.5 m from the root end of the blade and extends to the tipon both a leading edge and trailing edge side of the molds.

In some embodiments, the removable strip includes a handle at the end ofthe removable strip.

In some embodiments, removable strips are disposed at approximately1,500 mm, 12,000 mm, and 27,500 mm from the root end.

In some embodiments, the removable strip is dispensed from a dispensingcart, wherein the dispensing cart is external to the blade mold andtranslates along the blade span with the removable strips dispensedlaterally into the mold.

In some embodiments, the dispensing cart is disposed above the mold,with the removable strips dispensed downwardly into the mold. In someembodiments, a segment of a removable strip is dispensed proximate theroot and extended to the tip of mold. Additionally or alternatively, theremovable strip is installed onto the mold flange and cut at the 1.5 mmark from the root.

In some embodiments, the spar cap and mold split lines remain free ofany removable strips. Additionally, an opening can be formed in thevacuum bag to access the end of the removable strip.

In some embodiments a guide to create a predefined flow path for resindistribution is employed, wherein the removable strip does not breakthrough the guide upon removal.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and are intended toprovide further explanation of the disclosed subject matter claimed.

The accompanying drawings, which are incorporated in and constitute partof this specification, are included to illustrate and provide a furtherunderstanding of the method and system of the disclosed subject matter.Together with the description, the drawings serve to explain theprinciples of the disclosed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of various aspects, features, and embodiments ofthe subject matter described herein is provided with reference to theaccompanying drawings, which are briefly described below. The drawingsare illustrative and are not necessarily drawn to scale, with somecomponents and features being exaggerated for clarity. The drawingsillustrate various aspects and features of the present subject matterand may illustrate one or more embodiment(s) or example(s) of thepresent subject matter in whole or in part.

FIG. 1 depicts an exemplary embodiment of vacuum bag removal for a windturbine blade mold.

FIG. 2 depicts an exemplary embodiment of vacuum bag removal for a windturbine blade mold with a glass fiber layup segment.

FIG. 3 depicts an exemplary embodiment of vacuum bag removal for a windturbine blade mold with a bond cap flange.

FIGS. 4-7 depict an exemplary locations for installation of a vacuum bagremoval strip within a blade mold.

FIG. 8 depicts an exemplary locations for installation of a vacuum bagremoval strip within a blade mold.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

Reference will now be made in detail to exemplary embodiments of thedisclosed subject matter, an example of which is illustrated in theaccompanying drawings. The method and corresponding steps of thedisclosed subject matter will be described in conjunction with thedetailed description of the system.

In accordance with an aspect of the disclosure, a method of removing avacuum bag from a composite mold is provided. Removable strips areplaced around the perimeter of the component parts and across the partsto create natural break points in the consumable materials used duringmanufacture of a composite product, e.g. wind turbine blade. The vacuumbag, and other consumable layers, are placed over the removable stripsuch that when the strips are pulled, the strip tears, in a controlledand complete manner, through each layer of consumables. This eliminatesthe need to use a knife/scissor to remove the finished product, therebyavoiding risk of injury.

In some embodiments, the removable strips are configured as zip stripsas a means to quickly remove bagging and consumable materials from acured part. The removable strip strapping dimensions are variableaccording to the process it is applied to and ease of use. For purposeof illustration and not limitation, one embodiment of the strapping hada thickness of 0.028″, break strength 820 LBS, melting point 490° F.,width 0.5″, however it is to be understood that the particularstructural characteristics of the removable strips can vary according tothe application and particular components being manufactured.

In operation, the removable zip strip(s) are placed on non-sanding tapeand positioned directly on glass (glass fiber) where non-sanding tape isnot present. Release film perforated, Release Ease Teflon, Omega, GreenFlow Media, and vacuum bag are all placed over the top of thesematerials. After the turbine blade part is infused with resins and curedthe end of the removable zip strips are cut free from the consumablesand then pulled (e.g. manually) out of the manufactured part. The actionof pulling the zip strips out of the infused part tears through all theconsumables. Additionally, the zip strips provide for a predictable andcontrollable tear line so that undesired deviation and damage toneighboring components or materials is avoided.

In accordance with an aspect of the disclosure, the removable zip stripsare easily removed from the manufactured part, sections out theconsumables used during manufacture, and eliminates the need to cut witha knife or other tool which greatly reduces the risk of injury. Further,once all the removable zip strips are removed the consumables areremoved from the part and bundled up with the removable zip strips usedas strapping to tie the consumables together. In addition to the removalof consumables along the perimeter of blade skins (half a wind blade)the removable zip strips leave an impression where removed that is slickand creates an ideal location for tacky tape to be applied for aperimeter bag (in order to retain the shell in mold) installation.

In an exemplary embodiment of the disclosure, the disclosed processassists in disassembly and removal of equipment and consumables employedduring manufacture of composite products, e.g., debagging on skin molds.A removable zip strip(s) (10, 20) is placed around the mold on a clampedge between a top clamp edge (100) and a bottom clamp edge (200) asshown in the zoom-in views captioned in FIGS. 1-3. As shown, removablezip strips start at 1.5 m from the root end of the blade and run to thetip on both leading edge (LE) and trailing edge (TE) side of the molds.However, in some embodiments the removable strip can be placed at theroot of the mold, and across the root of the mold such that theremovable strips completely encompass or surround the perimeter of themold. An adhesive, or takifier, can be used to attach the removable zipstrips to the glass fiber and the non-sanding tape (NST), which caninclude a fabric material to serve as a secondary bonding surface onparts of a fiberglass part. The terminal ends of the removable zip stripcan be wrapped with a material, e.g. duct tape, that allows both foreasy visual identification as well as manual gripping. Additionally, ahandle 15, 25, 35 or pull tab can be included at the end of theremovable strip to facilitate tearing/removal. In some embodiments theentirety of the removable strips lie entirely under the vacuum bag, andcan only be accessed after curing of the resin and cutting into thevacuum bag.

In some embodiments, additional removable strips (10, 20, 30) can beplaced at the following locations (measured relative to the root end):1,500 mm, 12,000 mm, and/or 27,500 mm as shown in FIG. 2. As shown inthe illustrated embodiment, the removable zip strips can be placed toextend across the blade from mold split line to mold split line. In someembodiments, the removable zip strips can be positioned to ensure theydo not extend past mold split lines (as shown in FIGS. 4-6). Similarly,the removable strips are positioned such that they do not extend up overthe bond cap flange and do not extend out onto the mold flange. Thisapproach can be employed as an abundance of caution approach, ensuringthat no undesired puncturing/piercing of the bag occurs in these regionswith sharp curvatures. However, it should be understood by artisans ofordinary skill that the present disclosure is not limited to suchconfigurations, and that the removable strips can extend along anyportion of the mold. As shown in exemplary FIG. 2, the removable stripscan extend to the edge/boundary of the mold, if so desired.

During installation of the removable zip strips, a supply cart whichdispenses the removable zip strips can be stationed near the root ofmold, external to the mold. A segment of a zip strip is dispensed anddragged or carried to the tip of mold to ensure sufficient length isapportioned. Once the appropriate length is dispensed from the supplycart, the zip strip is installed onto the mold flange and cut at the 1.5m mark from the root end. This is repeated for both leading edge andtrailing edges of the blade mold. The removable strips that run in thechordwise direction can similarly be dispensed from a supply cart. Thelength desired can be determined by measuring the chord length (andaccounting for non-linear geometry of the mold contour). Once thedesired length is obtained, the zip strip can be cut or severed from thesupply stock via scissors. The zip strip dispensing cart can be mobileand positioned alongside the blade mold on the shop floor.Alternatively, the zip strip dispensing cart can be elevated (eithersuspended from above, or provided with a scaffold or stilt-like featureto raise it off the shop floor) such that zip strips can be dispensedand allowed to fall into place under the guidance of a steeringmechanism that is part of the dispenser, or by manual placement). Aspreviously noted, during dispensing and positioning of the removable zipstrip, care should be taken to ensure the zip strips do not extend orbridge over the auxiliary spar cap, nor extend past the mold split lineoutside of the blade.

In accordance with an aspect of the disclosure, the goal is to quicklyremove consumables with natural breaks created by tearing up the zipstrips. The zip strips can then serve a secondary function of serving asa means to consolidate and contain the consumables. This reduces thechance of foreign-object-debris from accidentally being left within themold or manufactured component. Additionally, in some instances wherethe zip strip runs under pleats in the bag when debagging the operatorcan cut the bag to re-adjust and remove any undesired pleats.

During installation, the following material layers are positioned abovethe removable zip strips: Blue Perf; Omega; Brown Peal Ply; Green Flow;Breather; Tape; and the Vacuum bag. These are consumable materials thatare used during infusion of the blade, and discarded after the resin hassufficiently cured. In some embodiments a non-sanding material can beprovided under the removable strips, which serves to provide a texturedsurface on the, e.g. fiberglass, component. As shown in the exemplaryembodiment of FIG. 2, the removable zip strip 10 is positioned above theglass fiber (90), which is positioned above the mold (80).

In some embodiments, an additional safeguard or quality controlinspection can be included to ensure that the fiber, e.g. glass, isnever installed over the removable strips. Similarly, safeguards can beimplemented to ensure that non-sanding tape is never positioned over theremovable strip. These safeguards can prohibit accidental, andpermanent, bonding of the “removable” strip to the component beingmanufactured. In accordance with another aspect of the disclosure, theremovable strips are provided with a uniform shape and size, whichallows for rapid and universal application of the strip at any desiredlocation on the mold.

As shown in FIGS. 7-8, after curing of the composite structure, the“debagging” of the component can commence. In this exemplary embodiment,an incision is made in the bag 1000 to access the end of the removablezip strip (10). Then the operator can pull the strip upward to cut ortear through the upper layers of material (as described above). In someembodiments; a guide can be used to create a predefined flow path forthe resin. This guide can take a variety of shapes, including an omegaor “Ω” shape. In such embodiments, the removable strip does not breakthrough the guide, when the resin is dispensed and cured. Accordingly, alever, hammer, cutting device, or “F-bar” (i.e. upside down bar with 2prongs on it in the shape of an upside down F) can be employed to breakthe guide so that the operator can continue to pull the removable stripfrom under the consumables to propagate the tear.

In accordance with another aspect of the disclosure, the chordwiseremovable zip strips can be dispensed independently and one at a time,or simultaneously. In some embodiments, the dispensing apparatus caninclude a gantry or guide mechanism that can be set to the desiredlocation (relative to the blade root, or relative to adjacent dispensinglocations) to ensure proper positioning of the zip strip.

The preferred setting of the presently disclosed technique is in themanufacture of epoxy and polyester resin parts. While the exemplaryembodiment focuses on wind turbine blade manufacture, this process canbe used in the fabrication of other composite parts e.g., marine,transportation, rides, sculpture, aircraft/military, civilinfrastructure, construction, appliance/business, consumer,corrosion-resistant equipment, and electrical component installations.

While the disclosed subject matter is described herein in terms ofcertain preferred embodiments, those skilled in the art will recognizethat various modifications and improvements may be made to the disclosedsubject matter without departing from the scope thereof. Moreover,although individual features of one embodiment of the disclosed subjectmatter may be discussed herein or shown in the drawings of the oneembodiment and not in other embodiments, it should be apparent thatindividual features of one embodiment may be combined with one or morefeatures of another embodiment or features from a plurality ofembodiments.

In addition to the specific embodiments claimed below, the disclosedsubject matter is also directed to other embodiments having any otherpossible combination of the dependent features claimed below and thosedisclosed above. As such, the particular features presented in thedependent claims and disclosed above can be combined with each other inother manners within the scope of the disclosed subject matter such thatthe disclosed subject matter should be recognized as also specificallydirected to other embodiments having any other possible combinations.Thus, the foregoing description of specific embodiments of the disclosedsubject matter has been presented for purposes of illustration anddescription. It is not intended to be exhaustive or to limit thedisclosed subject matter to those embodiments disclosed.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the method and system of thedisclosed subject matter without departing from the spirit or scope ofthe disclosed subject matter. Thus, it is intended that the disclosedsubject matter include modifications and variations that are within thescope of the appended claims and their equivalents.

What is claimed is:
 1. A method of removing a vacuum bag from a windturbine blade mold comprising: forming a wind turbine blade componentwithin a mold; providing at least one removable strip, the at least oneremovable strip disposed around at least a portion of a perimeter of thewind turbine blade component, disposing at least one consumable layerabove the at least one removable strip; disposing a portion of a vacuumbag above the at least one removable strip; pulling the at least oneremovable strip, wherein a pulling force tears through the at least oneconsumable layer and the vacuum bag.
 2. The method of claim 1, whereinthe at least one removable strip tears through the at least oneconsumable layer in a predetermined path.
 3. The method of claim 1,wherein the at least one removable strip has a thickness ofapproximately 0.028 inches, a width of approximately 0.5 inches, a breakstrength of approximately 820 pounds, and a melting point ofapproximately 490° Fahrenheit.
 4. The method of claim 1, wherein the atleast one removable strip is placed directly on glass.
 5. The method ofclaim 1, wherein once all of the at least one removable strip isremoved, the at least one consumable layer and vacuum bag are tied withthe at least one removable strip.
 6. The method of claim 1, wherein theat least one removable strip imparts a recess in the wind turbine bladecomponent after removal.
 7. The method of claim 6, further comprisingapplying tacky tape at the recess.
 8. The method of claim 1, wherein theat least one removable strip is disposed around the mold on a clamp edgebetween a top clamp edge and a bottom clamp edge.
 9. The method of claim1, wherein the at least one removable strip has a first end disposed at1.5 m from a root end of the wind turbine blade component and extends toa tip on both a leading edge and trailing edge side of the mold.
 10. Themethod of claim 1, wherein the at least one removable strip includes ahandle at an end of the at least one removable strip.
 11. The method ofclaim 1, wherein the at least one removable strip is disposed at anapproximate distance of one of 1,500 mm, 12,000 mm, or 27,500 mm from aroot end.
 12. The method of claim 1, wherein the at least one removablestrip is dispensed from a root of the mold to a tip.
 13. The method ofclaim 12, wherein the at least one removable strip is dispensedlaterally into the mold.
 14. The method of claim 12, wherein the atleast one removable strip is dispensed downwardly into the mold.
 15. Themethod of claim 12, wherein a spar cap and split lines of the moldremain free of the at least one removable strip.
 16. The method of claim1, wherein a segment of the at least one removable strip is dispensedproximate to a root of the mold and extended to the tip of the mold. 17.The method of claim 1, wherein the at least one removable strip isinstalled onto a flange of the mold and cut at the 1.5 m mark from aroot of the mold.
 18. The method of claim 1, wherein an opening isformed in the vacuum bag to access an end of the at least one removablestrip.
 19. The method of claim 1, further comprising a guide to create apredefined flow path for resin distribution.
 20. The method of claim 19,wherein the at least one removable strip does not break through theguide upon removal.